Currencies: The previously invincible U.S. dollar is sliding versus the Chinese yuan and Japanese yen. What gives?

Don’t look now, but the Chinese yuan is mounting something of a comeback against the U.S. dollar, while the previously battered Japanese yen also shows signs of life.

The U.S. dollar fetched 7.116 renminbi USDCNY, as the Chinese currency is officially known, in onshore trade Tuesday, after trading below its 200-day moving average. The dollar had traded at more than 7.35 renminbi, its strongest since 2007, as recently as September.

And…